The Voltage and Current Characteristics of Breakdown in Transformer Oil under Impulse Voltage

This paper presents an experimental investigation on transformer oil dynamic breakdown characteristics when subjected to impulse voltage. The dynamic characteristics of the discharge were explored by examining the instantaneous variations of current and voltage at the instant of breakdown. A dedicated test cell was constructed to contain the insulating oil. A sphere-sphere electrodes gap of variable length was used for the experiments. Series of tests have been conducted through a non-inductive resistor of 50?, connected in series with the test cell for three different inter-electrodes gaps; 1mm, 2.5 mm and 5mm. Other Series of test have been conducted for 1mm inter-electrodes gap, without the use of non-inductive resistor, and through different non-inductive resistors: 50?, 4.8 k? and 9.6…